Chemical equation with "●" symbol

Question

How to write this equation (the ● is like the +). I'm using {chemist} package for ordinary equations.

 ROO● + AH → ROOH + A●

Answer 1

With ● you probably mean the Lewis representation of an electron?

You mention the chemist package which is part of XyMTeX. XyMTeX has the commands \chemradicalA[]{} and \chemradicalB[]{} for denoting lewis electrons. They are described in XyMTeX's new manual (published only a few weeks ago to CTAN, 790 pages long!) section 23. Lone Pairs and Radicals.

\documentclass{article}
\usepackage{chemist,xymtex}
\begin{document}

\begin{center}
  \ChemForm{%
    RO\chemradicalA[2]{O} \, + \, AH
    \reactrarrow{0pt}{1cm}{}{}
    ROOH \, + \, \chemradicalA[2]{A}
  }\\
  \ChemForm{%
    RO\chemradicalB[1]{O} \, + \, AH
    \reactrarrow{0pt}{1cm}{}{}
    ROOH \, + \, \chemradicalB[1]{A}
  }
\end{center}

\end{document}

---

Here are a few alternative possibilities using other packages than XyMTeX:

\documentclass{article}
\usepackage[version=3]{mhchem}
\usepackage{chemformula}[2013/11/04]
\usepackage{chemfig}

\newcommand*\pkg[1]{\texttt{#1}}
\begin{document}

\pkg{mhchem}:\par
\ce{ROO. + AH -> ROOH + A.} (actually wrong)\par
\ce{ROO^. + AH -> ROOH + A^.}

\pkg{mhchem} and \pkg{chemfig}:\par
\ce{\Lewis{0.,ROO} + AH -> ROOH + \Lewis{0.,A}}

\pkg{chemformula}:\par
\ch{ROO. + AH -> ROOH + A.} (actually wrong)\par
\ch{ROO^. + AH -> ROOH + A^.}\par
\ch{"\chlewis{0.}{ROO}" + AH -> ROOH + "\chlewis{0.}{A}"} (needs an up to date
version)

\pkg{chemformula} and \pkg{chemfig}:\par
\ch{"\Lewis{0.,ROO}" + AH -> ROOH + "\Lewis{0.,A}"}

\pkg{chemfig}\par
\schemestart
  \Lewis{0.,ROO} \+ AH
  \arrow
  ROOH \+ \Lewis{0.,A}
\schemestop

\end{document}

The versions without chemfig (except the one with \chlewis) are not completely correct as they actually are typesetting the adduct dot and not an electron (the wrong spacing in the chemformula-only version tells it...)